Oscillator with electrodynamic drive and electromagnetic detection, especially for use in an electronic clock

ABSTRACT

An oscillator of the swinging-mass type, especially for use in an electronic clockwork wherein an amplifier feedback circuit is provided between a pickup coil and a drive coil electromagnetically coupled with the swinging mass. The swinging mass is formed with a pair of oppositely poled permanent magnets spaced apart by a distance less than the magnetic cross-section of the coil means constituting the pickup and drive coils.

0 United States Patet 1 1 [111 3,713,047 Ketterer 1 Jan. 23, 1973 OSCILLATOR WITH [56] References Cited ELECTRODYNAMIC DRIVE AND ELECTROMAGNETIC DETECTION, UNITED STATES PATENTS ESPECIALLY FOR USE IN AN 3,046,460 I 7/1962 Zemla ..58 23 A ELECTRONIC CLOCK 3,327,190 6 1967 Reich ..318/l28 3,487,629 1/1970 Takamune ct a1 ..318/l32 X [75] Inventor gg 'gz iggg Blumberg Black 3,509,437 4/1970 Hashimura ..33l/116M x [73] Assignee: Firma S. L. Kroewerath & Co., 'f 9 Kfminski Blumbergschwarzwald, Germany Assistant ExammerS1egfr1ed H. Grlmm Attorney1(arl F. Ross [22] Filed: Dec. 7, 1970 211 Appl. No.: 95,661 ABSTRACT An oscillator of the swinging-mass type, especially for [30] F i A li i p i i D use in an electronic clockwork wherein an amplifier D 9 1969 G P 19 61 6 feedback circuit is provided between a pickup coil and many a drive coil electromagnetically coupled with the [52] 331/1161 58/23 A 318/128 swinging mass. The swinging mass is formed with a I 331/154 pair of oppositely poled permanent magnets spaced 5 Int. CL 3/04, H02k 33/18, H03b 5/30 apart by a distance less than the magnetic cross-sec- [58] Field of Search.33l/1l6 M, l54;58/23 11,23 A, tion of the coil means constituting the pickup and 58/23 AC, 28 A; 310/36; 318/128, 129, 132

drive coils.

12 Claims, 7 Drawing Figures PATENTEUJAH 23 1973 3113 5 7 sum 1 [IF 3 Edmund Kefferer IN VEN TOR.

Attorn y PATENTEDJAN23 I973 3,713 047 sum 2 or 3 F|G.312Cl FIG 2c 51 32? 5455 55 5A 42 as 2L 30 290 L 33 19.1 EJI .E Li 5 ER 1 2 }36 22,23 1 25 Edmund Kefferer IN VEN TOR.

Attorney pmmgnms ma 3,713,047

SHEET 3 [IF 3 Edmund Kefferer IN V EN TOR.

Attorney OSCILLATOR WITH ELECTRODYNAMIC DRIVE AND ELECTROMAGNETIC DETECTION, ESPECIALLY FOR USE IN AN ELECTRONIC CLOCK FIELD OF THE INVENTION My present invention relates to a swinging-mass oscillator or electromechanical transducer for converting electrical energy into periodic mechanical move- BACKGROUND OF THE INVENTION It has already been proposed to provide means for converting electrical energy into periodic mechanical movement for operating clockworks and like systems wherein the mechanical member is coupled with a load, e.g., gearing operatively connected with the hands of a clock or watch face. The present invention is concerned with such systems as make use of angular oscillation of the mechanical member and, in particular, to electrodynamic drive and electrodynamic pickup arrangements for the indicated purposes.

It has already been suggested, in this regard, to provide a balance for an electronic watch or a drive means for a clockwork of this type which makes use of drive and sensing coils disposed along the path of a magnetic mass formed by the balance member.

In general, the sensing coil detects the passage of the magnetic mass and is connected through an amplifier, usually powered by an electric-energy source such as a battery, to a drive coil which electromagnetically reacts with the magnetic mass to induce further oscillations, a restoring force being supplied to maintain the angular oscillation. An angular oscillator of the character described can thus be said to include a rotatably journaled mass, biased into a rest position by a restoring means such as a spring, electrodynamic drive means, e.g., a coil positioned along the path of this mass, electrodynamic sensing means for detecting the passage of the mass, and a circuit including an amplifier between the detectingcoil and the drive coil. Since both coils may be combined in a single set of turns or may be superimposed one upon the other, I prefer to use the term coil arrangement to designate the one or more coils constituting the drive and detection arrangement. The swingable mass may include a permanent magnet poled to react with the magnetic field of the coil arrangement, the latter being energized with a timing determined by the circuitry such that oscillation of the mass is promoted. One member of the generator, e.g., the mass or the coil arrangement, thus constitutes the rotor while the other member, e.g., the coil arrangement or the mass, constitutes the stator. The axis of the permanent magnet and the axis or axes of the coils lie substantially parallel to one another and to the axis of the angularly oscillating member and hence approximately perpendicular to the path of the relative movement of the mass and the coil arrangement.

The resulting system is a contactless transducer for converting electrical energy into mechanical oscillations which can be applied to a clockwork and hence offers advantages over wiper and switch systems and even mechanical timing drives.

Existing electrodynamic oscillators of the type generally described have disadvantages which have reduced their value for many purposes. For example, the drive systems are often relatively massive and prone to breakdown as a result of imbalance or lack of mass distribution. Secondly, it has been found that greater precision is obtained and electrical perturbations are eliminated when a relatively large mass and long are of swing are provided. This involves the use of larger and more powerful coils which, in conventional systems, has given rise to the danger of electromagnetic or mechanical self-locking of the balance member upon the generation of an extraneous electrical signal. This problem is all the more pronounced because increasing stability of the oscillations is associated with increasing oscillation amplitude, increasing magnetic size and higher magnetic field intensity. Thirdly, the prior-art oscillators are characterized by a fluctuating oscillation period and a dependency upon the drive voltage, the temperature and mechanical factors.

OBJECTS OF THE INVENTION It is therefore the principal object of the present invention to provide an improved electromechanical oscillation generator whereby the aforementioned disadvantages can be obviated.

It is another object of my invention to provide a system for transforming electrical energy into periodic mechanical oscillation in which the period is substan tially independent of the applied voltage and the ambient temperature.

A further object of my invention is to provide an electrodynamic angular-oscillation generator particularly for use in conjunction with a clockwork, in which self-blocking signals cannot arise and greater electrical efficiency is obtained.

SUMMARY OF THE INVENTION These objects are attainable, in accordance with the present invention, which is based upon my discovery that, when the single magnetic mass of conventional rotors is replaced by a pair of oppositely poled permanent magnets, the interaction between the electromagnetic coil means and the permanent magnet field provides a unique opportunity for eliminating the disadvantages of the earlier systems. Provided that the two permanent magnets are relatively closely spaced, i.e., are separated from one another by a distance equal approximately to the height of the coil and, therefore, approximately half the diameter of the coil, and the center to center spacing between the electromagnets is approximately equal to the diameter of the coil, the output of the coil means during the pulse-generating half cicle is characterized by a short-duration steepflank pulse flanked by two shallow opposite-polarity pulses. When control is effected along the steep flanks of the main pulse, therefore, accurate regulation can be obtained without the control sensitivity characterizing earlier systems. Furthermore, when the system is used in conjunction with a transistor amplifier of appropriate construction, the pulses may be used to trigger the power signal during part of a cycle and to cancel the power signal during another part of the cycle, thereby ensuring consistent operation of the oscillator without self-blocking thereof.

The electrodynamic oscillator of the present invention, which is preferably used to operate a clockwork, comprises a moving member which is oscillatable along a generally planar path and a stationary member fixed relative to the path, the former being advantageously the rotor while the latter is the stator. An electromagnetic coil means in the form of a disk is mounted on the stationary member adjacent the path and has an induction cross-section which lies in a plane parallel to that of the path and is disposed adjacent the latter. The oppositely poled permanent magnets are mounted upon the swinging member and produce a magnetic field generally perpendicular to the plane of the path and adapted-to be cut by the coil. An important characteristic of the present invention, therefore, is that the permanent magnets each have a magnetic cross-section (in a plane parallel to the plane of the path) of a width, measured along the path, which is less than the width of the induction cross-section of the coil and of a spacing less than the width of this induction cross-section as taken along the path. The system operates with an amplifier means responsive to a signal induced in the coil means and adapted to produce a power signal which is applied to the coil means to drive the angularly oscillating member.

In an embodiment of the invention, each of the permanent magnets is subdivided into a pair of permanent magnet portions aligned with one another and mounted on disks of magnetic permeable material flanking the disk-shaped coil such that the permanent-magnet portions extend toward the latter. Alternatively, the coil means can include a pair of disk-shaped coils while the permanent magnets are swung along their path between these members.

The amplifier means according to the present invention comprises a pair of opposite-conductivity transistors, i.e., an NPN transistor and a PNP transistor, one constituting a power transistor while the other is a control transistor. The emitter-collector circuit of the power transistor preferably includes the coil winding of the device and may be bridged by a complex voltage divider containing a series network of ohmic resistances and a capacitor (defining an RC network). The signal developed at the capacitor is applied to the base of the control transistor whose emitter-collector circuit may include a voltage divider which, in turn, is tied to the base of the power transistor. A diode is preferably bridged across the coil which may be connected in series with an additional collector resistor or may constitute the collector resistor for the power transistor by itself. For temperature stabilization and the like, I prefer to form at least one of the resistors of the voltage divider, which is connected to the base of the power transistor, as a temperature-sensitive element, e.g., a thermistor.

I have found that this construction permits electrical energization of the balance wheel such that a large angle of swing can be imparted to the latter between an initial position and a final rest position, this angle exceeding lSOf when the balance wheel is biased by a torsion spring and 30 when a pendulum is employed. Furthermore the device prevents blocking signals from impeding oscillation of the wheel and is highly compact, thereby enabling it to be used to drive a clockwork. The unit is self-starting, moreover, and the power pulses may be applied, as noted below, so as to be effective in one direction only.

The amplifier circuitry, according to the present invention, differs from the prior art systems in that the feedback signal is derived from a complex voltage divider. The triggering of the power transistor is effected by a DC coupling between the first and second stages and the second triggering pulse of each signal is nullified so that the on state of the transistor is not triggered thereby. Assume, as will be apparent hereinafter, that the two permanent magnets induce a high-amplitude pulse of one polarity flanked by a pair of minima constituting pulses of the opposite polarity. The first of these low-amplitude pulses may be employed to trigger the power transistor into its on state and, in conventional amplifier systems used with a twopart magnetic system, the corresponding second pulse would likewise be effective to trigger the system again into an on state. The circuit of the present invention, however, excludes this possibility.

As is also apparent from the following specific description, the time constant of the RC network is not especially critical and it suffices that this time constant is smaller than the half period of the system. The undesired signal is stored and dissipated over the interval until the first pulse of the next passage of the oscillating member.

DESCRIPTION OF THE DRAWING The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is a schematic plan view of the coil and magnet system of the electrodynamic oscillator according to the present invention and a graph of the inductive output of this system as a function of the displacement of the magnet in two positions thereof;

FIG. 2a is a front-elevational view of the oscillator omitting unessential parts;

FIG. 2b is a plan view of the oscillator of FIG. 2a, partly in cross section along the line IIb IIb thereof;

FIG. 2c is a side-elevational view partly in section along the line He IIc of FIG. 2b;

FIG. 2d is a view similar to FIG. 20 but illustrating another embodiment of the present invention;

FIG. 3 is a circuit diagram of the amplifier arrangement for the electrodynamic oscillator of FIGS. 2a 2c; and

FIG. 4 is a graph of the voltage against time at the collector of the driving transistor, and measured to the negative terminal of the DC source, in which the relationship between the induced voltage to the voltage drop across the resistors upon conductivity of this transistor is apparent.

SPECIFIC DESCRIPTION In FIG. 1, the disk-shaped coil 1 is shown schematically together with the circular arc-segmental path 2 of the permanent magnets 3 and 4. The axis of the coil 1 is substantially perpendicular to the plane of the path and lies slightly within the path 2 while the permanent magnets 3 and 4 are approximately perpendicular to the path 2 as well and are parallel to one another and to the axis of the coil 1.

According to the principles of the present invention, however, the permanent magnets 3 and 4 are magnetically poled in opposite directions to induce magnetic fluxes which can be visualized as running into and out of the plane of the paper as represented by the circle in magnet 4 and the cross of magnet 3. The cross 5 of the latter magnet, of course, represents the tail of the arrow representing north-to-south magnetic polarization while the point 6 represents the head or tip of the arrow. The prior position of the magnets 3 and 4 is represented by broken lines 7 and 8 respectively.

As will also be apparent from FIG. 1, each of the permanent magnets 3, 4 has a diameter d which is small by comparison with the diameter D of the coil 1 and the electromagnetic flux generated thereby or the outlines of its turns as represented by the shaded portions in FIG. 1. The center-to-center spacing of the permanent magnets 3, 4 is represented at S and is approximately equal to the diameter D as illustrated while the diameter d is preferably less than the radius 12 or 13 (winding height) of the coil. The center-to-center distance S between the permanent magnets may be approximately equal to the winding height l2, 13.

When the permanent magnets 3, 4 lying along the dot-dash line representing the arcuate path 2 of the swinging member of the oscillators pass across the outline of the coil 1, a voltage is generated in the coil by electromagnetic induction or an electric current traversing the ,coil induces a force in the electromagnet which can be considered as applied tangentially to the path 2. Each permanent magnet, therefore, can be considered as generating an output represented by the curve 9 in the coil and, conversely, a potential applied by the coil can be considered to produce a force which is represented by the curve 9 as a function of the position of the permanent magnet represented along the abscissa. The force or electric output is plotted along the ordinate.

The curve 10 represents the resultant output in terms of the position of the center point 11 intermediate the permanent magnet 3, 4. The curve 10 comprises a short-duration positive pulse flanked by a pair of negative pulses, the troughs of which are symmetrically located on opposite sides of the positive maximum. These troughs will herein after be referred to as minima, the transitions between the positive pulse and the minima being steep flanks along one of which the points 14 and 15 are plotted. The peak amplitude for the positive pulse is obtained when the distance between the axes of the permanent magnets 3 and 4 is approximately equal to the diameter of the coil 1 as previously indicated.

From the graph 10 it is also apparent that the function of the systems factor for the indicated position of the centerpoint 11 has its steepest region at the point indicated at 14. In this region, the system is readily controllable, i.e., a small change in position is represented by a large variation in potential. Hence the adjustment of the system can be carried out with high precision. This adjustment is not especially critical since, as represented at point 15, the slope of the steep flanks of the positive pulse remains constant over a long portion of the flanks. Critical adjustments of the type which characterized earlier systems are not relevant here.

In FIGS. 20 2c, the structure of the electrodynamic oscillator is illustrated in greater detail. The device thus comprises a base plate 21 carrying the spacer columns 22 and 23 upon which the guide plate 24 is mounted. In the base plate 21 and the guide plate 24 a shaft 25 is journaled to carry the angularly swingable oscillator or rotor member 26. The shaft 25 also carries a pair of soft magnetic (magnetically permeable) disks 27, 28 which together constitute a balance wheel and, to reduce weight, are provided with quarter-segmental cutouts 28a 28b. These cutouts also serve to reduce eddy currents which might otherwise act to damp the oscillations of the balance wheel.

In FIG. 212 only the lower disk 28 can be seen. The disks 27 and 28 carry on their underside and upper side, respectively, each a pair of small permanent magnets 29a, 29b and 30a, 30b whose induction axes are perpendicular to the path of oscillation and which are oriented as represented by the pole designation N and S, respectively. In other words, the permanent magnets on the disks 27 are oppositely poled so that their South and North poles, respectively, are turned toward the coil 35 while the permanent magnets 29b and 30b of the disks 28 are poled in opposition to the permanent magnets 29a and 30a and have their North and South poles, respectively turned toward the coil. Each pair of permanent magnets 29a, 29b, therefore, produces lines of magnetic force which run perpendicular to the turns of the coil and are oppositely poled from the lines of magnetic force of the other pair. The magnetic flux directions are represented by the arrows 31 and 32. Along the side of the disks 27, 28 opposite the permanent magnets 29a, 29b and 30a, 30b, respectively, are provided counterweights 33, 34 which prevent undesired stress at the disks 27 and 28 and eliminate unbalanced swing.

The air gap between magnets 29a and 29b and magnets 30a and 30b is represented at 36 and sweeps across the coil 35 which constitutes a disk as best seen in FIG. 2a. Since disks 27 and 28 are of magnetic material and the shaft 25 is similarly magnetic, these members constitute a magnetic shunt or yoke between the poles of the permanent magnets 29a 29b, 30a and 30b turned away from the air gap and augment the induction in the latter. The coil 35 has a thickness c which is approximately equal to the width of the air gap 36 and is substantially planar so that only those lines of force which are almost precisely perpendicular to the coil are effective in accordance with the principles of the present invention. As a result, the magnetic lines of force induce an electric current in the coil 35 and, in turn, react with a magnetic field generated in the coil 35 to provide the tangential force necessary to swing the balance wheel as previously described.

The coil 35 is encapsulated in insulating synthetic resin in the form of a plate 38.

The foot 38 of the plate is provided with pins 39 and 40 for one set of turns of the coil 35 and pins 41, 42 for the other set of turns of this coil, a spacer 43 mounting the plate 37 by his foot 38 upon the support 21. A screw 44 passes through the insulating material of both the foot 38 and the spacer 43 and is threaded into the support 21. When a single set of turns is used in the coil, no electrical shunt is required at 45 and such a shunt may be provided where two sets of turns is used.

In FIG. 2d, I have shown an alternative embodiment of the invention which represents a kinematic reversal of the system of FIGS. 2a 20. In this embodiment, two soft-magnet disks 71, 72, similar to those of FIGS. 2b, and a support 73 of synthetic resin are fixed to the shaft 74. The disks 71 and 72, together with the shaft 74 form a magnetic yoke or shunt.

In this embodiment, a support base 83 carries via spacers 81 and 82 and an appropriate screw-type fastening, a pair of coils 77, 78 of disk-shaped configuration in superimposed registry on opposite sides of the pair of permanent magnets 75, 76 carried by the support 73. The permanent magnets 75, 76, of course, are spaced apart as described with respect to the permanent magnets 3 and 4 of FIG. 1 and the magnets 29a and 30a of FIG. 2a.

The coils 77 and 78 are imbedded in synthetic-resin support plates 79 and 80 and are separated by the spacer 81 while being mounted on the foot 82 fixed to the support 83 as noted earlier. In this embodiment, the magnets do not swing on opposite sides of the coil but are disposed between a pair of coils, one of which can be used for producing the oscillating force while the other serves as a pickup coil for the amplifier. The remainder of the device is similar to that of FIGS. 2a 2c and the operation is similar.

Similar results can be obtained with the modification of FIG. 2a wherein the permanent magnets 29a and 30a, together with the counterweight 33 are omitted and the magnetic disk 27 is located closely above the coil 35. This type of modification of the system of FIG. 2d provides the magnets 75, 76, instead of on support 73, upon the disk 71 whereby the coil 77 with the support plate 79 and the intermediate support disk 73 can be eliminated. Either of these modifications has been found to be particularly successful where the electrodynamic oscillator is to have a limited height.

Within the angled base plate 21 (see FIG. 20) a clockwork (not shown) may be provided when the electrodynamic oscillator is to be used as the period controller of an electronic clock. In this case, a pawl wheel 52 carried by the shaft 25, on each of its half swing, engages the starwheel 53 of the clockwork. I prefer to constitute the starwheel 53 with teeth of such configuration that it is entrained by the pawl 52 only during the half cycle of each oscillation in which the magnetic power pulse is applied.

The flange 48 of the base plate 21 may be used to secure the entire assembly of oscillator rotor 26, clockwork, coil 35 and the electronic circuit 51 to a common housing and may be composed of electrically insulating and at least partially transparent material. The housing may also be provided with a casing to receive the battery which constitutes the energy source for the amplifier circuit. The housing itself is generally designed to be affixed more or less loosely or releasably, e.g., by hanging, to the clock face and supporting structure. While the balance wheel is designed to be returned by an outside force in the direction opposite the power pulse, this means may be a spiral or torsion spring 54 as shown in FIG. 2a which is anchored to shaft 25 along its inner periphery and at its outer side to the plate 24 at 55; an alternative return arrangement may include a pendulum whose weight is located at an adjustable distance from its pivot and which coincides with the shaft of the balance wheel. In the latter case, the oscillator member includes not only the disks 27, 28 and the shaft 25, but also the stem and weight of the pendulum with which the permanent magnet arrangement is mechanically coupled.

On the foot 38, with solder junctions to the terminals 39 42, is provided a printed-circuit panel 46 to which the transistors 47 and 48 and other electronic components 49, 50 are secured in the usual manner. The result is an amplifier circuit 51, schematically shown in FIG. 3, which generates the power pulses. Instead of the printed circuit technique as illustrated in FIG. 2a, I may make use of other microcircuitry such as thick film or thin film circuits or integrated circuits secured directly to the pins or terminals 39-42.

In FIG. 3, I have represented the permanent magnets at 101 and 102, swingable on an arm about a fulcrum at 103, the latter representing the shaft. It will be understood that the permanent magnets will be mounted on a balance wheel as described in connection with FIGS. 2a 2d or the modifications thereof previously described. The coil is diagrammatically shown at 104. The ohmic resistance of the coil 104 and, if desired, an additional ohmic resistor 112 (as the collector-bias resistance) lies in series with the positive terminal 105 of the battery and the collector 107 of a transistor 108 whose emitter 109 is tied to the negative terminal 110 of the battery. The silicon NPN transistor 108 has a base 127 which is tied at 126 to a voltage divider represented by a series-connected pair of resistors 123, 124 whose tie point is shown in 125. The coil 104 and resistor 112 are shunted by a diode 113 poled to resist passage of positive current from the positive terminal 105 to the collector 107.

In parallel to the collector-emitter network 107, 109 of the transistor 108, I provide a complex voltage divider consisting of a series network of a resistor 114, a condenser 115, and a resistor 116, this network being disposed between the diode 113 and the negative terminal 110 of the direct current source. The tie point 117 of this network, between the resistor 116 and the capacitor 115, is connected via lead 118 to the base 119 of PNP control transistor 120. The emitter 121 of the transistor is connected to the positive bus bar 106 while the collector 122 is connected via the resistors 123, 124 to the negative bus bar 1 11. As already noted, the tie point 125 between the resistors 123 and'124, is connected via lead 126 to the base 127 of the power. transistor 108. For greater stabilization of the circuit against variations in the input voltage and temperature fluctuation, one of the resistors 123, 124, may be a temperature-responsive resistor (e.g., a thermistor) and will have, in the case of substitution for resistor 124, a negative temperature coefficient.

While the operation of the feedback-coupled amplifier using the voltage divider 114-116 will be readily apparent, it should be noted that a negative pulse delivers to the base 1 19 a signal producing a current increase in the coil 104 and, therefore, a further voltage drop at the voltage divider; conversely, a positive pulse applied to the base of the transistor 119 gives rise to a current drop in the coil 104 and a corresponding increase in the voltage at collector 107 and, consequently, at the tap 117. In either case, therefore, the feedback tendency will tend to reverse the previously established mode.

The circuit operation will best be understood from the consideration of FIG. 4 in which the voltage at collector 107 of FIG. 3 is represented along the ordinate as a function of time plotted along the abscissa. The voltage is measured against the negative bus bar 111.

As described in connection with FIG. 1, the potential at the collector is a function of the position of the centerpoint 11 of the balance wheel and, in the rhythm of the half-cycle period l/2, positive pulses 152, 154 and negative pulses 151, 153 will develop which are practically superimposed upon the drive potential 155. When one considers only the pulses generated by pure mechanical displacement of the oscillator, it will be apparent that one could obtain the positive pulse 156, 157, then a negative pulse of approximately twice the height as represented at 158, 159, and finally another pulse 160, 161 of a height equal to the first. correspondingly, there is generated first a negative pulse 152, 153, a positive pulse of twice the height at 164, 165, and finally a negative pulse 166, 167 during the positive portion of the function 152, 154. It can also be seen that low amplitude and corresponding lowvoltage pulses are of proportionately long duration and highamplitude pulses of correspondingly short duration.

When the amplifier circuit is considered to be included in the system, there is generated a switchover state at 168, the point at which the negative pulse 158 exceeds a threshold value whereby the voltage on the collector of the power transistor 108 drops to the value 169. This stable state is terminated by a positive pulse 160 which cuts off the transistor. When the transistor is initially triggered, the voltage change at the collector is delayed by the time constant network represented by the RC circuit 114-116 of FIG. 3 whereby, during the interval up to the next swing of the magnets, the potential assumes the configuration of branch 171 of the curve.

The'next triggered condition 172 of the transistor (represented by the positive function 152) is triggered by the first negative pulse 162 and is terminated by the subsequent positive pulse 164 which is transformed by the capacitor to a positive value 173 such that the subsequent negative pulse cannot trigger the transistor into a conductive state until decay of the charge upon the capacitor. The process is repeated with respect to the functions 153 and 154.

Indicia 174-177 represent the null or zero position of the oscillator. The first pass of the angularly oscillating member which" generates a pair of positive pulses and the negative pulse of double height, produces a drive pulse which is represented at 155 and is maintained over substantially the entire interval for which the permanent magnets cross the outline of the coil. The next.

clockwork and, if this concept is coupled with a pawl arrangement whereby the clockwork is disengaged on the return stroke, the assembly has a low-power consumption. The system is also, as can be seen from FIG.

4, amplitude limiting because of its natural characteristics and able to avoid self-blocking conditions without the use of mechanical or electrical damping.

The improvement described and illustrated is believed to admit of many modifications within the ability of persons skilled in the art, all such modifications being considered within the spirit and scope of the invention except as limited by the appended claims.

I claim:

1. An electrodynamic oscillator comprising:

a moving member oscillatable along a generally planar path and a stationary member fixed relative to said path;

electromagnetic coil means mounted on one of said members and defining an induction cross section in a plane parallel to that of said path and disposed adjacent same;

pair of oppositely poled permanent magnets mounted on the other of said members for generating a magnetic field generally perpendicular to the plane of said path and cut by said coil means upon relative displacement of said members, said permanent magnets each having a magnetic cross section of a width less than the width of said induction cross section of said coil means and a spacing less than said width of said induction cross-section as taken along said path; and

amplifier means responsive to a signal generated in said coil means for applying a power signal thereto to drive said moving member, said stationary member comprising a support, said moving member being pivotally mounted on said support for arcuate displacement of said permanent magnets thereon, said electromagnetic coil means being mounted on said support and having a circular disk-shaped coil with an induction axis parallel substantially to the pivotal axis of said moving member, said permanent magnets being of circular cross-section and extending substantially parallel to one another and substantially perpendicular to the plane of the path and parallel to said axes;

a magnetically permeable yoke for reinforcing said magnetic field, the diameter of each of said permanent magnets being less than the winding height of said coil and said permanent magnets having a center-to-center spacing substantially equal to the diameter of said coil, said amplifier means comprising:

a power transistor and a control transistor of opposite types,

a complex voltage divider connected to the collector of the power transistor and including a capacitor,

a feedback path connecting said capacitor with the base of said control transistor,

a further voltage divider connected to the collector of said control transistor, and

means connecting the base of said power transistor to said further voltage divider, said coil means being connected in series with said collector of said-power transistor to a positive terminal of a direct-current source and being shunted by a diode resisting positive-signal transmission from said positive terminal to said collector of said power transistor, the bias resistance of said collector of said power transistor being at least in part formed by the ohmic resistance of said coil means, said control transistor being a PNP transistor and said power transistor being a NPN transistor, one side of said complex voltage divider being connected to the tie point of said diode and the collector of the power transistor and the other side of said complex voltage divider being connected to the negative terminal of said source, said complex voltage divider including a pair of resistors respectively connected to the collector of said power transistor and said negative terminal and a capacitor between said resistors and in series therewith, the feedback path between said control transistor and said complex voltage divider including a lead connected to the base of said control transistor and to the junction of said capacitor with the said resistor connected to said negative terminal, the emitter of said control transistor and the emitter of said power transistor being respectively connected to said positive terminal and to said negative terminal.

2. The electrodynamic oscillator defined in claim 1 wherein said moving member has a rest position in which the axis of one of the permanent magnets is offset by approximately half the winding height of said coil from the induction axis thereof in the direction in which said power signal drives said moving member.

3. The electrodynamic oscillator defined in claim 1 wherein each of said permanent magnets comprises a pair of axially aligned permanent-magnet portions magnetically coupled by said yoke and flanking said coil on opposite sides thereof.

4. The electrodynamic oscillator defined in claim 1 wherein said electromagnetic coil means includes a pair of axially spaced aligned disk-shaped coils, said path passing through said coils.

5. The electrodynamic oscillator defined in claim 1 wherein said further voltage divider includes a thermistor.

6.'The electrodynamic oscillator defined in claim 1 wherein said amplifier means is formed as a microcircuit mounted directly on said support.

7. The electrodynamic oscillator defined in claim 1, further comprising a clockwork mounted upon said support and restoring means for returning said moving member along said path in the direction opposite the direction of the force applied to said movable member by said power signal.

8. An electrodynamic oscillator, comprising:

a moving member oscillatable along a generally planar path and a stationary member fixed relatively thereto:

electromagnetic coil means mounted on oneof said members and defining an induction cross-section in a plane parallel to that of said path and disposed adjacent same;

a pair of oppositely poled permanent magnets mounted on the other of said members for generating a magnetic field generally perpendicular to the 6 plane of said path and cut by said coil means upon relative displacement of said members, said permanent magnets each having a magnetic cross-section of a width less than the width of said induction cross-section and a spacing less than the width of said induction cross-section as taken along said path; and

amplifier means responsive to a signal generated in said coil means for applying a power signal thereto to drive said moving member, said amplifier means including:

a first transistor and a second transistor of oppositeconductivity type, said coil means being connected between the collector of thefirst transistor and a corresponding first terminal of a direct-current source,

a complex voltage divider connected to the collector of said first transistor and to an opposite second terminal of said direct-current source and including a capacitor,

a feedback path connecting said capacitor with the base of said second transistor,

means I connecting the emitter of said second transistor and the emitter of said first transistor respectively to said first and second terminals,

a further voltage divider connected between the collector of said second transistor and said second terminal, and

means connecting the base of said first transistor to said further voltage divider, and wherein:

the bias resistance of said first transistor is at least in part formed by the ohmic resistance of said coil means;

said complex voltage divider includes a pair of resistors respectively connected to the collector of said first transistor and said second terminal, and a series capacitor between said resistors and in series therewith; and

said feedback path includes a lead connected to the base of said second transistor and to the junction of said series capacitor and the said resistor connected to said second terminal.

9. The electrodynamic oscillator defined in claim 8 wherein: I

said coil means is shunted by a diode resisting positive signal transmission from said first terminal to said collector of said first transistor.

10. The electrodynamic oscillator defined in claim 9 wherein the said first transistor is a power transistor of NPN -conductivity type, the said second transistor is a control transistor of PNP-conductivity type, the first terminal of the said direct current source is the positive one, and the second terminal is the negative one.

1 l. The electrodynamic oscillator defined in claim 9 further comprising a support for said members, a clockwork mounted upon said support and restoring means for returning said moving member along said path in the direction opposite the direction of the force applied to said movable member by said power signal.

12. An electrodynamic oscillator, comprising:

a moving member oscillatable along a generally planar path and a stationary member fixed relatively thereto;

electromagnetic coil means mounted on one of said members and defining an induction cross-section in a plane parallel to that of said path and disposed adjacent same;

a pair of oppositely poled permanent magnets mounted on the other of said members for generating a magnetic field generally perpendicular to the plane of said path and cut by said coil means upon relative displacement of said members, said permanent magnets each having a magnetic cross-section of a width less than the width of said induction cross-section and a spacing less than the width of said induction cross-section as taken along said path;

a magnetically permeable yoke for reinforcing said magnetic field; and

amplifier means responsive to a signal generated in said coil means for applying a power signal thereto to drive said moving member, said amplifier means including:

a first transistor and a second transistor of oppositeconductivity type, said coil means being connected between the collector of the first transistor and a corresponding first terminal of a direct-current source,

a complex voltage divider connected to the collector of said first transistor and to an opposite second terminal of said direct-current source and including a capacitor,

a feedback path connecting said capacitor with the base of said second transistor,

means connecting the emitter of said second transistor and the emitter of said first transistor respectively to said first and second terminals,

a further voltage divider connected between the collector of said second transistor and said second terminal, and

means connecting thebase of said first transistor to said further voltage divider, and wherein:

the bias-resistance of said first transistor is at least in part formed by the ohmic resistance of said coil means;

said complex voltage divider includes a pair of resistors respectively connected to the collector of said first transistor and said second terminal, and a series capacitor between said resistors and in series therewith; and

said feedback path includes a lead connected to the base of said second transistor and to the junction of said series capacitor and the said resistor connected to said second terminal. 

1. An electrodynamic oscillator comprising: a moving member oscillatable along a generally planar path and a stationary member fixed relative to said path; electromagnetic coil means mounted on one of said members and defining an induction cross section in a plane parallel to that of said path and disposed adjacent same; a pair of oppositely poled permanent magnets mounted on the other of said members for generating a magnetic field generally perpendicular to the plane of said path and cut by said coil means upon relative displacement of said members, said permanent magnets each having a magnetic cross section of a width less than the width of said induction cross section of said coil means and a spacing less than said width of said induction cross-section as taken along said path; and amplifier means responsive to a signal generated in said coil means for applying a power signal thereto to drive said moving member, said stationary member comprising a support, said moving member being pivotally mounted on said support for arcuate displacement of said permanent magnets thereon, said electromagnetic coil means being mounted on said support and having a circular disk-shaped coil with an induction axis parallel substantially to the pivotal axis of said moving member, said permanent magnets being of circular cross-section and extending substantially parallel to one another and substantially perpendicular to the plane of the path and parallel to said axes; a magnetically permeable yoke for reinforcing said magnetic field, the diameter of each of said permanent magnets being less than the winding height of said coil and said permanent magnets having a center-to-center spacing substantially equal to the diameter of said coil, said amplifier means comprising: a power transistor and a control transistor of opposite types, a complex voltage divider connected to the collector of the power transistor and including a capacitor, a feedback path connecting said capacitor with the base of said control transistor, a further voltage divider connected to the collector of said control transistor, and means connecting the base of said power transistor to said further voltage divider, said coil means being connected in series with said collector of said power transistor to a positive terminal of a direct-current source and being shunted by a diode resisting positive-signal transmission from said positive terminal to said collector of said power transistor, the bias resistance of said collector of said power transistor being at least in part formed by the ohmic resistance of said coil means, said control transistor being a PNP transistor and said power transistor being a NPN transistor, one side of said complex voltage divider being connected to the tie point of said diode and the collector of the power transistor and the other side of said complex voltage divider being connected to the negative terminal of said source, said complex voltage divider including a pair of resistors respectively connected to the collector of said power transistor and said negative terminal and a capacitor between said resistors and in series therewith, the feedback path between said control transistor and said complex voltage divider including a lead connected to the base of said control transistor and to the junction of said capacitor with the said resistor connected to said negative terminal, the emitter of said control transistor and the emitter of said power transistor being respectively connected to said positive terminal and to said negative terminal.
 2. The electrodynamic oscillator defined in claim 1 wherein said moving Member has a rest position in which the axis of one of the permanent magnets is offset by approximately half the winding height of said coil from the induction axis thereof in the direction in which said power signal drives said moving member.
 3. The electrodynamic oscillator defined in claim 1 wherein each of said permanent magnets comprises a pair of axially aligned permanent-magnet portions magnetically coupled by said yoke and flanking said coil on opposite sides thereof.
 4. The electrodynamic oscillator defined in claim 1 wherein said electromagnetic coil means includes a pair of axially spaced aligned disk-shaped coils, said path passing through said coils.
 5. The electrodynamic oscillator defined in claim 1 wherein said further voltage divider includes a thermistor.
 6. The electrodynamic oscillator defined in claim 1 wherein said amplifier means is formed as a microcircuit mounted directly on said support.
 7. The electrodynamic oscillator defined in claim 1, further comprising a clockwork mounted upon said support and restoring means for returning said moving member along said path in the direction opposite the direction of the force applied to said movable member by said power signal.
 8. An electrodynamic oscillator, comprising: a moving member oscillatable along a generally planar path and a stationary member fixed relatively thereto: electromagnetic coil means mounted on one of said members and defining an induction cross-section in a plane parallel to that of said path and disposed adjacent same; a pair of oppositely poled permanent magnets mounted on the other of said members for generating a magnetic field generally perpendicular to the plane of said path and cut by said coil means upon relative displacement of said members, said permanent magnets each having a magnetic cross-section of a width less than the width of said induction cross-section and a spacing less than the width of said induction cross-section as taken along said path; and amplifier means responsive to a signal generated in said coil means for applying a power signal thereto to drive said moving member, said amplifier means including: a first transistor and a second transistor of opposite-conductivity type, said coil means being connected between the collector of the first transistor and a corresponding first terminal of a direct-current source, a complex voltage divider connected to the collector of said first transistor and to an opposite second terminal of said direct-current source and including a capacitor, a feedback path connecting said capacitor with the base of said second transistor, means connecting the emitter of said second transistor and the emitter of said first transistor respectively to said first and second terminals, a further voltage divider connected between the collector of said second transistor and said second terminal, and means connecting the base of said first transistor to said further voltage divider, and wherein: the bias resistance of said first transistor is at least in part formed by the ohmic resistance of said coil means; said complex voltage divider includes a pair of resistors respectively connected to the collector of said first transistor and said second terminal, and a series capacitor between said resistors and in series therewith; and said feedback path includes a lead connected to the base of said second transistor and to the junction of said series capacitor and the said resistor connected to said second terminal.
 9. The electrodynamic oscillator defined in claim 8 wherein: said coil means is shunted by a diode resisting positive signal transmission from said first terminal to said collector of said first transistor.
 10. The electrodynamic oscillator defined in claim 9 wherein the said first transistor is a power transistor of NPN -conductivity type, the said second transistor is a control transistor of PNP-conductivity type, the first terminal of the said direct current source is the positive one, and the second terminal is the negative one.
 11. The electrodynamic oscillator defined in claim 9 further comprising a support for said members, a clockwork mounted upon said support and restoring means for returning said moving member along said path in the direction opposite the direction of the force applied to said movable member by said power signal.
 12. An electrodynamic oscillator, comprising: a moving member oscillatable along a generally planar path and a stationary member fixed relatively thereto; electromagnetic coil means mounted on one of said members and defining an induction cross-section in a plane parallel to that of said path and disposed adjacent same; a pair of oppositely poled permanent magnets mounted on the other of said members for generating a magnetic field generally perpendicular to the plane of said path and cut by said coil means upon relative displacement of said members, said permanent magnets each having a magnetic cross-section of a width less than the width of said induction cross-section and a spacing less than the width of said induction cross-section as taken along said path; a magnetically permeable yoke for reinforcing said magnetic field; and amplifier means responsive to a signal generated in said coil means for applying a power signal thereto to drive said moving member, said amplifier means including: a first transistor and a second transistor of opposite-conductivity type, said coil means being connected between the collector of the first transistor and a corresponding first terminal of a direct-current source, a complex voltage divider connected to the collector of said first transistor and to an opposite second terminal of said direct-current source and including a capacitor, a feedback path connecting said capacitor with the base of said second transistor, means connecting the emitter of said second transistor and the emitter of said first transistor respectively to said first and second terminals, a further voltage divider connected between the collector of said second transistor and said second terminal, and means connecting the base of said first transistor to said further voltage divider, and wherein: the bias-resistance of said first transistor is at least in part formed by the ohmic resistance of said coil means; said complex voltage divider includes a pair of resistors respectively connected to the collector of said first transistor and said second terminal, and a series capacitor between said resistors and in series therewith; and said feedback path includes a lead connected to the base of said second transistor and to the junction of said series capacitor and the said resistor connected to said second terminal. 